Fatigue failure of a nut-bolt connection characteristically occurs at the interface between the engaged and non-engaged threads of the bolt since relatively high stress levels are found adjacent the first and second mated threads thereof. By creating a degree of flexibility or "buffer zone" in the first several threads of the nut, while maintaining required tensile strength characteristics, the stress level at the interface between the engaged and unengaged portions of the bolt is reduced. Such flexibility effects a relatively uniform load distribution and transfer of stress to all of the mating threads.